The present invention relates to a system for automatically detecting defects in articles that are produced from transparent materials. In particular, the invention is directed to the automatic inspection of transparent containers such as glass and plastic bottles.
Glass bottles and other transparent containers are subject to a number of different types of defects that can be occasioned by impurities within the glass material itself, by improper molding techniques resulting in fissures and non-uniform glass distribution, or by rough handling procedures. Accordingly, the bottles must be individually inspected to reject faulty ones after they emerge from an annealing lehr and before they are filled or shipped. In the past, such inspection has been carried out visually by human inspectors. However, such an approach is not entirely satisfactory not only because of the labor expenses that are incurred but also because of the inconsistencies that can result from human error. For example, as the inspector grows tired near the end of an inspection period he is more likely to miss a fault in a bottle that quickly passes through an inspection station.
More recently, various types of systems have been proposed for automatically inspecting defects in bottles. Example of such systems are disclosed in U.S. Pat. Nos. 4,165,277 and 4,338,028. These prior systems are generally limited to the detection of one flaw, or at most a few types of flaws, such as side fissures, for example. Accordingly, the requirement for a human inspector still exists because of the likelihood that flaws other than those detected by the automatic systems could be present. Moreover, these systems may be less effective than a human inspector in terms of the percentage of faulty containers that are detected.
Furthermore, when the same type of defect consistently occurs during production it is desirable to locate the source of the flaw and correct it. While a human inspector may be able to do this, heretofore known automatic systems do not provide such a capability. Thus, the prior systems are not totally satisfactory from the standpoint of eliminating the need for visual inspection.